This invention relates to cargo container handling in general, and specifically to a tool to assist a longshoreman in inserting and removing self-locking swivel stacking pins employed in the loading and stacking of containerized cargo on board ships and loading docks.
The use of container ships to transport containerized cargo has become one of the primary means for shipping. Standard size containers and pier-side crane systems substantially increase productivity while reducing manpower required, and hazards incurred, in loading and unloading freight transporting ships. Cargo containers are provided with metal reinforcing corners at top and bottom surfaces thereof. These metal reinforced corners provide attachments for turnbuckle attached tie-down cables and are provided with openings through flat steel plates therein to receive latches on spreader mechanisms of cranes for lifting and positioning the containers on board ships or on pier-side docks. In the prior art, after a first container had been positioned by a crane operator, a longshoreman "latcher" released the spreader mechanism from the first, or bottom, container and a second longshoreman "stacking pin installer" normally placed individual stacking pins in the plates of each of the first container's exposed upper reinforced corners to permit stacking of a second container onto the first container. After the second container had been stacked thereon, a lever of each of the stacking pins had to be rotated to lock the first and second containers together. Similarly, when the second container was removed from the first container, the stacking pin levers had to be rotated to unlock the containers.
Such stacking pins served to support the entire weight of the second "stacked" container in spaced relationship over the first container with a space therebetween permitting passage of tie-down cables. These stacking pins have varied in structural shape and from ship-to-ship, and have, in the past, normally been 6-10 inches in length and weighed up to 20 pounds or more each.
U.S. Pat. No. 5,390,970 to William H. Gray discloses a shipping container stacking pin tool for inserting such stacking pins without the use of ladders in first containers. In this regard, prior to the Gray invention, the stacking pins were placed in first containers by hand using ladders.
Although the Gray invention simplified placement of stacking pins for first containers, it did very little for such pin placement for second, third and fourth containers in a stack. Thus, it was still often necessary for workers to "ride the spreader bar" on cranes to install and remove pins, which was somewhat dangerous and time consuming.
Now, a new type of stacking pin, a self-locking swivel stacking pin, has been developed which can be inserted at the bottom of a container. That is, a first, or bottom, container is put in place without stacking pins at bottom or top corners thereof. A second container, which is to be placed on the first container, is then lifted by a crane and a "stacking pin installer" inserts the self-locking swivel stacking pins at the bottom corners of the thusly lifted second container. Each of the self-locking, or automatic, swivel stacking pins has a pin housing with a spacer section and top and bottom insert sections on opposite sides of the spacer section, top and bottom swivel locking heads respectively adjacent the top and bottom insert sections, and a rotatable axle rigidly attached to the top and bottom swivel locking heads and passing through the housing. The top and bottom insert sections are rectangular in shape so that they match rectangular holes in the corner plates of the containers. The top and bottom insert sections and the top and bottom swivel locking heads are elongated in a direction perpendicular to an axis of the rotatable axle. A biasing spring in the housing normally biases the top and bottom locking heads, via the axle, to be rotated so that they do not align with their respective top and bottom insert sections and the top and bottom locking heads are attached to the rotatable axle so that they do not align with one another. The biasing spring is one of the features that makes these swivel stacking pins self-locking, or automatic. A tether-type hand-crank mechanism is provided to allow an operator to counter the biasing spring, thereby rotating the axle to place the top swivel locking head parallel with its respective insert section. Once the operator has done this, he can insert the top swivel locking head and top insert section into a hole of the plate at the lower edge of the second container. Using the hand-crank mechanism, the operator then allows the swivel locking head to rotate (due to the biasing spring in the housing) so that it is no longer aligned with its insert section, to thereby latch, or lock, the self-locking swivel stacking pin on the container. After four such pins are placed at the second container's lower edge, the second container is lifted above the first container and the stacking pins, which are mounted on the second container, are aligned with the rectangular holes at top corners of the first container. The second container is then lowered so that the bottom swivel locking heads of the swivel stacking pins engage edges defining the holes in the first container's top corner plates and these bottom swivel locking heads, due to their shape, automatically rotate to align with their respective bottom insert sections. In doing this, they do not cause the top locking heads to align with the top insert sections. Once the lower swivel locking heads pass through the first container's holes, the biasing springs in the housings automatically rotate the axles back to their home positions with both top and bottom swivel locking heads being locked onto their respective containers. This automatic locking procedure can also be used for stacking the third, fourth and fifth containers without the necessity of a worker "riding the spreader bar" on the crane.
In this position, for unlocking, the hand-crank mechanisms must be reached for rotating the axles and thereby unlocking the swivel stacking pins from the containers when this is desirable.
Although these new self-locking swivel stacking pins have many benefits over earlier stacking pins for container stacks higher than two containers, they have the detriment that when a "stacking pin installer" is installing one of them he is standing directly under a lifted (second, third, etc.) container, which is extremely dangerous. Further, when a self-locking swivel stacking pin is not mounted on a container, it is difficult to operate its hand-crank mechanism for rotating its axle and the attached swivel locking heads. Still further, the self-locking swivel locking pins are quite awkward in shape and extremely heavy (up to 20 pounds or more) and therefore difficult for an operator to grip, actuate, and install.
Because of the above problems, it is an object of this invention to provide a swivel stacking pin tool which can be used for picking up self-locking swivel stacking pins from a deck, or the ground, and rotating the top and bottom swivel locking heads thereof while manipulating them for inserting them into container corner plates. Further, it is an object of this invention to provide such a self-locking swivel stacking pin tool which allows an operator to install a self-locking swivel stacking pin without placing his hand or body immediately below a raised container.